XmlSerializable

You can write your own serialization mechanism for your class by XmlSerializable interface. You have to implement only two methods:

public function toXml(\DOMElement $node, XmlSerializer $serializer);
public static function fromXml(\DOMElement $node, XmlDeserializer $deserializer);

Example

Time class:

class Time implements \Kadet\XmlSerializer\XmlSerializable {
    public $hours;
    public $minutes;
    public $seconds;

    public function toXml(\DOMElement $node, \Kadet\XmlSerializer\XmlSerializer $serializer)
    {
        $node->appendChild($node->ownerDocument->createElement(
            'seconds',
            $this->seconds + $this->minutes * 60 + $this->hours * 3600 // calculate total seconds
        ));

        return $node;
    }

    public static function fromXml(\DOMElement $node, \Kadet\XmlSerializer\XmlDeserializer $deserializer)
    {
        // create our object to fill
        $time = new Time();

        // read value from xml node
        $total = $node->getElementsByTagName('seconds')->item(0)->nodeValue;

        // calculate specific variables
        $time->seconds = $total % 60;
        $time->minutes = floor($total / 60) % 60;
        $time->hours   = floor($total / 3600);

        return $time;
    }
}

$time = new Time();
$time->hours   = 12;
$time->minutes = 15;
$time->seconds = 50;

Serialization of $time will result in:

<?xml version="1.0" encoding="utf-8"?>
<Time xmlns:s="urn:kadet:serializer" s:type="Time">
  <seconds>44150</seconds>
</Time>

And if you unserialize that xml you will get:

object(Time)#8 (3) {
  ["hours"]=>
  float(12)
  ["minutes"]=>
  int(15)
  ["seconds"]=>
  int(50)
}

As you can see serialized and unserialized objects are same, as predicted.